When I compared BG2 to KotOR, I wasn't talking about the plot, but rather the gameplay, and NPC development. It's the same core game, except that you control fewer characters thus removing much of the tactical gameplay in BG2, the roleplaying system is more limited, and the combat is a lot easier. Finally, NPC development is tied to your level instead of depending on time spent together, and location.
As for the plot, the twist was terribly hamfisted, and could be seen coming from a mile away, by a blind man standing in fog, wearing sunglasses, an eyepatch and with his hands over his eyes. Other than that, it did the job of keeping the game going.